One of the many crucial aspects of deck building is framing. A well-designed, carefully-crafted deck frame contributes to safe and stable composite decking. With that said, there are various concerns when designing a deck frame. Not only will you need to consider the materials you will be using, but you also need to know how well it can handle the load. One of the most commonly asked questions is, how far can a 2×6 decking span without any additional support? What are the span requirements that you have to meet?
Always Comply With the Local Codes
Before you build a deck, it’s best to get to know your local building codes. Consulting the local building department can help you understand the requirements and regulations set in place to ensure a durable, safe, and stable deck.
One of the many things you will find in your local codes is the standards for deck frames. You can find information about what material to use, how to build it, and more. Your local building codes can also tell you about span requirements, including how long joists will be and the distance between each one. Other information you can find includes proper foundation and footer installation. You’ll also know whether you need to install railings depending on the specific height listed in the building codes.
If you are building a deck or considering one, you’ll want to read and understand your local building codes as soon as possible. With that said, it may still come as unclear for some. If you are still unsure about span requirements, here are some things you should know.
Understanding Decking Frames
To better understand span requirements, you may need to know a few terms used in deck framing. The two most crucial parts of a deck frame are the beams and the joists. The decking beams or rafters are the load-bearing part that primarily supports the joists among a few other things, whereas the joists support the decking joists.
Beams and joists will need proper spacing to ensure structural integrity. If they are too apart, your deck will sag and fail when presented with too much load. On the other hand, installing them too close to each other will lead to unnecessary spending and workload.
A common term that you may encounter is OC or ‘on centre.’ It refers to the total distance of structural elements from each other starting at the centre, often used in joist spacing. For instance, a 16″ OC will mean that each joist is 16 inches apart from centre to centre. The closer joists to one another, the more stable and sturdy the deck will be. As previously mentioned, placing them too close can lead to many difficulties.
The joist span refers to the total distance a joist can support between the beams. It’s also the proper distance of the beams or other supporting elements for the joists so the deck joists will not sag. But how do you determine joist spacing and span requirements?
Deck Span Requirements
When determining how far a joist, there are many things to consider. Some of the most crucial aspects are the type of material you are using, including the grade for lumber, and the materials’ dimensions, among other things.
First thing you will consider is the material you will be using. Each type of lumber or deck material will have its strengths and weaknesses. But as for framing, the main factor you will want to look for is tensile strength. While some wood may be denser than other varieties, they may lack tensile strength. For instance, Cedar and Redwoods are more durable, but their tensile strength is less than Pine, Fir, or Larch.
Another crucial factor is the grade of the material. The better the quality of the material, the more span it generally allows. For instance, timber grading varies depending on where you live. In the UK, softwood timber grading ranges C16, C18, C24, to C30. A separate grading system for hardwood also exists, which are D24, D30, D40, D50, D60, and D70.
Lastly, the joists and beams’ dimensions affect how much it can handle. For decking, joists will often come in 2×6 to 2x12s. Generally, the wider the boards are, the longer the distance they can span. Now, let’s get back to the question. How far can a 2×6 span without support?
How Far Can a 2×6 Span?
As previously mentioned, many factors can affect span measurements. A 2×6 joist can span anywhere between 8′ for Cedar and Redwood to 9′ for Pine and Fir at 16″ OC. 12″ OC yields longer spans, while 24″ OC allows shorter spans. For other types of framing, such as composites, you will find the information on manuals and guidelines that the manufacturers will give you.
With that said, when determining the spans of your joists, beams, and other framing elements, it’s best to consult your local building codes first. Professional builders and installers can also give more in-depth details, as several situations and factors can affect deck spans.